package com.rsa;

import org.apache.commons.codec.binary.Hex;

import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * Created by lenovo on 2016/1/10.
 */

/*
        数字签名
 */
public class ImoocRSA2 {

    private static String src = "imooc security rsa2 ";

    public static void main(String[] args){
        jdkRSA();
    }

    public static void jdkRSA(){
        try {
            //1.初始化密钥
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(512);
            KeyPair keyPair  =keyPairGenerator.generateKeyPair();
            RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
            RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();

            //2.执行签名
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
            Signature signature = Signature.getInstance("MD5withRSA");
            signature.initSign(privateKey);
            signature.update(src.getBytes());
            byte[] result = signature.sign();
            System.out.println("jdk rsa sign : " + Hex.encodeHexString(result));

            //3.验证签名
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            signature = Signature.getInstance("MD5withRSA");
            signature.initVerify(publicKey);
            signature.update(src.getBytes());
            boolean bool = signature.verify(result);
            System.out.println("jdk rsa verify : " + bool);

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}
